Plastic coated shotgun pellets



Jan. 16, 1968 c. R. IRONS 3,363,561

PLASTIC COATED SHOTGUN PELLETS Filed Jan. 28, 1966 5/707 9un S/)e//,OOQ/Her Th er'm O a/0575b oo/ymer coaf/ny INVENTOR. C0rr0// A. #643,:

BY M19 HTTORNEY United States Patent Ofi 3,363,561 Patented Jan. 16,1968

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3,363,561 PLASTIC COATED SHOTGUN PELLETS Carroll R. Irons, Midland,Mich, assignor to The Dow Chemical Company, Midland, MielL, acorporation of Delaware Filed Jan. 28, 1966, Ser. No. 523,553 Claims.(Cl. 102-42) ABSTRACT OF THE DISCLQSURE This invention concerns plasticcoated shotgun pellets and relates to shotgun shells containing plasticcoated metal pellets.

It is common knowledge that in the use of a shotgun in the sports ofhunting, skeet shooting, and trap shooting, the shot pattern is mostimportant. This includes where the shot pellets fall in the target area,i.e. pattern uniformity, as well as how many pellets strike the target,e.g. pattern density.

It is known that a sleeve or tubular body casing of polyethyleneinserted around the lead shot pellets in a shotgun shell acts as acushion for the shot as it travels down the barrel of the gun, andprevents or substantially inhibits deformation of the shot that normallywould contact the barrel and results in approximately a 4 to 10 percentimprovement in pattern density. It is known that as a rule sphericalshot produce more uniform patterns than do deformed shot.

It is also known that shotgun patterns are often nonuniform, the shothaving a tendency to cluster and fall on the pattern board (or target)closely grouped together rather than uniformly spread out. This tendencyresults in patchy patterns or patterns with holes in them. Everyshotgunner, and particularly trap and skeet shooters, would dearly lovea shell that would avoid this tendency to patchiness or holes in theshot string.

An additional aspect to which this invention relates is that of anational conservation problem concerning the death by lead poisoning ofgreat numbers of waterfowl, especially ducks and geese who, while bottomfeeding in hunting areas, ingest the spent lead shot and grind it up intheir digestive process thus causing lead poisoning. Efforts are beingmade to solve this problem and this tragic waste of our waterfowl.

One proposed solution has been the use of an inert plastic coating forlead shot pellets.

Another proposed solution is the use of a nontoxic metal as a substitutefor the lead. So far, the most promising substitute appears to be ironor steel shot. The advantages of iron shot are that it would quicklyrust away in water, and, even if it were to be swallowed by the ducks,it would not poison them. Also, tests have shown that up to a range of40 yards, penetration with iron shot is often greater than that of leadshot in spite of the gravity differential between lead and iron of 11.35and 7.85 respectively. This is probably due to a higher veloc ityimparted to the lighter iron shot by a given powder loading. Beyondabout 40 yards the superiority of the heavier lead shot comes into play.However, especially in the case of skeet shooting and regulation trapshooting, the 40 yard limitation is unimportant since all targets aretaken within a 40 yard range. The same could be said of the average killmade by duck hunters. The big disadvantage of iron or steel shot is theextreme barrel Wear produced as the relatively hard shot traverses thebarrel. Although reduced barrel wear can be obtained by using a plasticsleeve or tubular body casing around the iron shot, this results in thedisadvantage of producing a tighter pattern which is undesirable forsome purposes such as skeet shooting where an open uniform pattern isneeded.

It is an object of this invention to provide shotgun shell shot, e.g.,iron or steel shot pellets, or predominantly iron or steel pellets,coated with a plastic. Another object is to provide iron or steel shotpellets coated with a plastic and suitable for use in the manufacture ofshotgun shells which coated pellets inhibit and substantially preventextreme barrel wear by substantially or completely eliminating contactbetween the barrel surface and the bare iron or steel shot. A furtherobject is to provide shot pellets coated with a tetrafiuoroethylenepolymer. Still another object is to provide shot pellets coated with analiphatic olefin polymer such as polyethylene or polypropylene. A stillfurther object is to provide a method for improving the shot pattern ofshotgun shells by coating the shot contained therein with a plasticwhich will not only protect the shot from deformation by contact withthe barrel of the gun, but will also prevent deformation resulting frompressure contact between contiguous shot.

The foregoing and additional objects and cognate advantages and benefitsof this invention are obtained by coating the shot pellets with aresinous thermoplastic polymer, e.g., polytetrafluoroethylene,polyethylene, polypropylene, or a synthetic polyamide resin.

In the drawings:

FIGURE 1 is a self-explanatory schematic partial section view of ashotgun shell containing shot pellets coated in accordance with thepresent invention.

FIGURE 2 is a self-explanatory enlarged cross-sectional elevational viewof one of the coated shot pellets shown in FIGURE 1.

The polymers to be employed for coating the shot must provide suflicientlubricity between the shot and the inner surface of the barrel of thegun with which it comes in contact so that extreme barrel wear isprevented. The polymer coating of the shot contained in a shotgun shellmust protect the shot not only from deformation caused by contact withthe barrel of the gun, but also from deformation resulting from pressurecontact between contiguous shot.

Among suitable polymers are the normally solid resinous thermoplastichomopolymers of tetrafluoroethylene, and copolymers consistingprincipally of from to 99 percent by weight of tetrafluoroethylene andfrom 1 to 15 percent by weight of hexafluoropropene, and polymers suchas polyethylene, polypropylene, and synthetic polyamide resins commonlyknown as nylon 6, nylon 66, or nylon 100. The homopolymers andcopolymers of tetrafluoroethylene, known to the trade as TeflonTEE-fluorocarbon resins, are preferred because of their good lubricitycharacteristics, although polyethylene, polypropylene and syntheticpolyamide resins are suitable.

The effect of extreme barrel wear by using plastic coated iron or steelshot can readily be determined by comparative tests, in which one ormore shotguns using the plastic coated iron or steel shot are comparedto one or more shotguns using the non-coated iron or steel shot. Theeffects on barrel wear can readily be observed and compared after asufliciently large number of shells are fired. In each such test, itwill be found that the plastic coated iron or steel shot produced nosignificant barrel wear, while the non-coated iron or steel shotproduced substantial or extreme barrel wear. It may be mentioned thathard, i.e., unannealed, iron or steel shot produce greater barrel wearthan do soft or annealed iron or steel shot.

The improvement in shot pattern resulting from the use of plastic coatedlead, iron or steel shot can also be readily determined by comparativetests. For example, by taking two substantially identical shotguns,placing two target boards containing a 30inch diameter target circle ata range of from 25 to 40 yards, with one gun using shells containingplastic coated lead, iron, or steel shot and the other using similar butnon-coated shot, and the firing of a sufficient number of shells at thetargets, the improved shot pattern of the gun firing the plastic coatedshot will be found. Not only will there be improvement in the number ofshot in the target, i.e., the pattern density, but also an improvementin pattern uniformity will be found.

The coating of the lead, iron, or steel shot pellets with thethermoplastic resin to form an impervious film, coating, or layer of thefused polymer about 0.1 mil to 2.0 mils thick on the surface of the shotcan be carried out in usual ways. The methods include dipping thepellets in a solution of the polymer in a solvent and evaporating thesolvent to leave a residue layer of the polymer covering the individualshot pellets, or using a fiuid bed technique such as contacting theheated lead, iron, or steel shot with the finely divided polymer in afluid bed, or suspended in a counter-current stream of air wherein thepellets, falling for example by gravity, contact the powdered polymerwhich adheres thereto and the powder and pellet are subsequently heatedor subjected to heating, e.g., by infrared lamps, such that the powderedpolymer coating is fused to form a continuous coating on the individualshot. The polymer coating can be formed by tumbling the lead, iron, orsteel shot in a drum with the powdered resinous polymer wherein thepolymer and shot are heated to sinter the powder into a continuousprotective coating, after which the coated shot are removed and heatedto fuse the polymer. In general, the heating of lead shot pellets shouldnot exceed a temperature of about 500 E, and is preferably carried outat temperatures not higher than about 480-485 F. in order to avoiddistorting of the spherical shot pellets. Iron or steel shot can beheated at higher temperatures.

The following examples illustrate ways in which the principle of theinvention can be applied, but are not to be construed as limiting itsscope.

Example I Number 4 lead shot intended for loading shotgun shells wascleaned of surface lubricants and oxide coating by shaking the shot inan aqueous slurry of a commercial kitchen cleaning powder for tenminutes, then washing the cleansed shot with water and drying the same.The cleansed shot were sprayed with an aqueous slurry of finely dividedpolytetrafluoroethylene and dried. The dried shot coated with thepowdered polytetrafiuoroethylene were heated in an air oven at 480-485F. for one hour to fuse the polytetrafluoroethylene particles into acontinuous coating, then were cooled to room temperature. The shot weresprayed with a second coating of an aqueous polytetrafluoroethyleneslurry and were dried, and the dried powdered coating fused by heatingthe shot in an oven at 480-485" F. for one hour as was done previously.The shot had a continuous fused coating of polytetrafiuoroethylene onthe surfaces. These coated lead shot are loaded into shotgun shells, andtested by firing at target boards 40 yards away against shellscontaining non-coated lead shot. An improved shot pattern is found.

Example 2 Hard iron shot, intended for loading shotgun shells andcorresponding in size to No. 6 lead shot, are immersed in a solution ofpolyethylene having a melt index of 5 dissolved in decalin at atemperature of C., and are removed, the solvent is evaporated and thepellets dried. The dried pellets are found to have a continuous surfacecoating of polyethylene. The coated pellets are loaded into shotgunshells and tested against shotgun shells containing non-coated and hardiron shot. Two target boards are set up at 40 yards, one for each gunrespectively using the polyethylene coated shot and the non-coated shotin the shells. After firing a sufficient number of shells, the coatedshot is found to produce an improved shot pattern. Also, no extremebarrel wear is found after prolonged use of the coated shot, whereasextreme barrel wear is found in the gun using the non-coated and hardiron shot.

Example 3 Number 6 lead shot pellets are coated with Zytel, asuperpolyamide resin, and loaded into shotgun shells, and tested againstshells containing noncoated lead shot. An improved shot pattern isproduced with the coated shot fired at target boards 25 yards away.

Example 4 Iron shot of a size corresponding to No. 6 lead shot arecoated with polypropylene, and loaded into shotgun shells. These aretest fired against shells containing non-coated iron shot at targets 35yards away. Extreme barrel wear is eliminated and an improved shotpattern results from the use of the coated iron shot.

I claim and desire to secure Letters Patent for:

1. Iron shot pellets suitable for loading shotgun shells having aprotective surface coating of a fused normally solid resinousthermoplastic polymer, said polymer selected from the group consistingof polytetrafluoroethylene, polyethylene, polypropylene and a syntheticpolyamide.

2. Shot pellets according to claim polymer is polytetrafiuoroethylene.

3. Shot pellets according to claim 1, wherein the polymer ispolyethylene.

4. Shot pellets according to claim 1, wherein the polymer ispolypropylene.

5. Shot pellets according to claim 1, wherein the polymer is a syntheticpolyamide.

6. Shotgun shells containing iron shot pellets having a protectivesurface coating of a fused normally solid resinous thermoplasticpolymer, said polymer selected from the group consisting ofpolytetrafiuoroethylene, polyethylene, polypropylene and a syntheticpolyamide.

7. Shotgun shells according to claim *6, wherein the polymer ispo-lytetrafluoroethylene.

8. Shotgun shells according to claim 6, wherein the polymer ispolyethylene.

9. Shotgun shells according to claim 6, wherein the polymer ispolypropylene.

10. Shotgun shells according to claim 6, wherein the polymer is asynthetic polyamide.

1, wherein the References Cited UNITED STATES PATENTS 2,257,878 10/1941Brennan 102-92.5 2,772,634 12/1956 Oberfell 102-42 2,919,647 1/1960 Dearet a1 102-42 2,928,348 3/1960 Zisman et a1. 10293 OTHER REFERENCESSmokeless Shotgun Powders, by Wallace Coxe; E. I. Du Pont, 1935, pp.6062.

BENJAMIN A. BORCHELT, Primary Examiner.

ROBERT F. STAHL, Examiner.

